Potentiometer thermostat



March 5, 1935. p, F- SHNERS POTENTIOMETER THERMOSTAT Filed May 20, 1951 31a/vento@ Pau Z Eln'z/e r;

VWGGY. :1mg/:L

. IDI..

Patented Mn.` s, 1935 y 1,993,687

UNITED STATES PATENT OFFICE POTENTIOMETER THERMOSTAT Paul F. Shivers, Wabash, Ind., assig'nor to Min neapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application May 20, 1931, Serial No. 538,864

4 Claims. (Cl. 20L-48) The present application relates to a potenthe oscillation of the lever 22 about the knife tioineter thermostat. The primary object of edges 20. the invention is to provide an instrument re- It will be obvious that the spring 16, being sponsive to temperature conditions impressed under tension tends to move the lever 22 in a 5 thereon and operable to control electrical circuits clockwise direction about its pivotal mounting 5 with which it is associated by minute variations. on the knife edges 2o. The upper end of the Further objects of the invention will appear as bellows 18 carries a stud 25 which is received in the description proceeds. a socket 26 formed in the lever 22 adjacent the To the accomplishment ofthe above and reportion 23 thereof. Obviously, the bellows 18 I l lated objects, my invention may be embodied in iSends 110 COllnereCl? the effect 0f the Spring 16 10 the form illustrated in the accompanying drawand, When Seid bellOWS iS expended, it Will move ing, attention being called to the fact, however, the level 22 in e Counter CIOCkWSe dreClOn,

that the drawing is illustrative only, and that overcoming `the tendency of the Spring 16.

change may be made in the specic construction The lever 22 Carries an arm 27 Which extends l illustrated and described, so long as the scope of rearwardly and downwardly behind the bellows l5 the appended claims is not violate@ 18 and behind the bracket 11. To the lower end Fig. 1 is a front elevation of an instrument em- O Seid erin may be Secured e Spring Contaot nbodying the present invention, the cover being ger 28 fOr e purpose later to be described.

removed; A core 29 mounted on the base 10 has wound Fig. 2 is a vertical section through such an thereon a coil 3o. One end of said coil is suitably 20 instrument. connected to a conductor 31, and the connection Fig. 3 is a fragmental section, similar to that of me? preferably he effected through the medium Fig, 2, of a .modified embodiment of the present of a metallic collar 32 clamped upon the end of invention; and said coil and suitably secured to said conductor 2s Fig. 4 is a diagram illustrative of the windings 3l The Opposite end 0f the Conductor 31 is Suit- 25 of the spools illustrated in Fig. 3. ably connected to a binding post 33 spaced from Referring more particularly to the drawing, it the bracket n and promoting u nqugh the in will be seen that the instrument comprises a base Sulatmg pas@ 10 to termma'te Wltmn an Outlet 1U of insulating material to which is secured a box 34 Whlch may be mountjed on the rear face of so bracket 11. said bracket is formed with a dewnthe bese 10- T0 the @pronte end- Of the C011 30 30 Wardly extending leg 12 carrying an ear 13 in there is connected a second conductor 35, the opin which a threaded spindle 14 is mounted for Poslte end of which 1S Conneted to 9 Second bind' rotation, but held against reciprocation. On the mg post 35' hkewlse extendmg through the base threadedperiien ofthe spindle 14 there is meuni- 10- 35 ed a nut 15 to which is secured the lower end of A mlm bmfimg post 37 projects through the 35 a Spring 16. base .10 and 'into the bracket 11, thus making The bracket 11 likewise provides a table it in decimal Contact with sind bracketwhich is secured the lower end of a bellows 18 A Cove? membm' 38 may be mummy secured t@ ned with a Suitable volatile fluid,` the base lo to house the mechanism above de 40 Adjacent its upper end, the bracket carries a smbed alud Said cover member is preferably 40 forwardly extending ear 19 carrying a pair of opformed with .m1, a'rcute. aperture 39 through positely projecting knife edge plates 20. A for- Whlch an amusw'ble mdlcator plate 40 and E' wardly projecting bifurcated plate 21 is likewise Stationary indicator @nger l may be Viewed' r@he plate 40 carries an arm 42 operatively associ' Gamed at the upper end 0f the bracket 11 *ma ated with the nut 15, se that rotation of the spinu 45 a lever 22 is operatively associated with said le M Mft th 1 t knife edges 2o and with said bifureaied plaie 2i. gf the mtnsg we. p a e as 1t Yanes the tenslon The lever 22 is formed adjacent its one end As will be obvious, if `one side of a source of With a' Concavconvex Portion 23 copemtmg electrical energy is connected to the binding ioost With the knife edges 20- Ar its Opposite end, 'me 37, and ii the other side oi said source is con- 50 lever 22 carries a pin 24 to which is secured the Elected, in pmueg through units to be controlled. upper end 0f the Spring 16. A portion of the leand thence to the respective binding posts 33 and ver 22 adjacent the last-mentioned end thereof is ad, and if the contact nnger 28 is in a neutral received between the furcations of the plate 21, position, the pctentials impressed upon said units said furcations therefore acting as stops limiting will be equal and opposite. Any variations in 55 the temperature impressed upon the bellows 18 will result in movement, in one direction or the other, of the lever 22; will result in consequent movement of the arm 27 and finger 28; and will thus change the position of the finger 28 on the coil 30. If it be presumed that such variation is a rise in temperature, then the finger 28 will be moved toward that end of the coil 30 to which the conductor 35 is connected, and the resistance in the following circuit will be reduced:-Power source, post 3'7, bracket 11, lever 22, arm 27, finger 28, coil 30, conductor 35, binding post 36, the unit connected to said post, and back to the current' source; while the resistance to current flow through the circuit including the conductor 31 will be increased.

A further embodiment of my invention is illustrated in Figs. 3 and 4. The structure therein illustrated is designed to provide for a very material variation in the resistances of the controlled circuits in response to an initial very small movement of the contactor. Referring more particularly to Figs. 3 and 4, it will be seen that I have illustrated the base 10 upon which is mounted the bracket 11; and that I have likewise illustrated a portion of the arm 27 carrying the contact finger 28.

A core 50, corresponding to the core 29 of Fig. 2, is suitably secured to the base 10 and carries a coil 51, the opposite ends of said coil being connected, by straps 52, or the like, to conductors, one of which is illustrated at 53. The conductor 53 is connected to a binding post 54 corresponding to the post 33, and it will be understood that the other conductor is likewise connected to an independent binding post corresponding to the post 36.-

A second core 55 is suitably mounted, in the illustrated embodiment, said core 55being mounted concentrically within the core 50. Said core 55 carries a coil 56, as shown.

Referring now more 4particularly to Fig. 4, it will be seen that the coil 51 is broken substantially at its center, so that it forms two sections 51a and 51h. The conductor 53 is connected to one end of the section 51a, and a second conductor 61 is connected to the opposite end of the section 51h. The end of the section 51a adjacent the center of the coil 51 is connected, by a lead 57, to one end 58 of the coil 56, and the corresponding end of the section 51h is connected by a lead 59 to the opposite end 60 of said coil 56. In Fig. 4, the separation between the adjacent ends of the sections 51a and 51b is materially exaggerated. In actual practice adjacent ends of said sections will be so close together that the contact finger 28, when in its neutral position, will contact the adjacent ends of both of said sections.

Obviously, when the finger 28 is in said neutral position, the coil 56 will be shunted out of both circuits, so that the resistances in the two circuits will be substantially equal. An almost imperceptible movement of .the finger 28, to the left, for instance, in Fig. 4, will effect a great variation in the resistances in the two circuits; since such movement will move the finger 28 out of contact with the section 51h. After such movement, only the section 51a will be in the circuit through the conductor 53, while the coil 56 will be connected in series with the section 51h in the circuit through the conductor 61.

I claim as my invention:

l. A circuit-controlling instrument comprising a core of angular cross-section, two coils of resistance wire wound on said core and spaced longitudinally thereof, the adjacent ends of said i coils being in close juxtaposition but out of electrical contact with each other, a third resistance element having its opposite ends connected, respectively, to the adjacent ends of said coils, at least a portion of said third resistance element being positioned within said core, and a contact member associated with an angular portion of said core and adapted to sweep said two coils and, at times, to bridge the adjacent ends of said coils, said contact member and the separated ends of said coils being connected in an electric circuit.

2. A circuit-controlling instrument comprising a core, two coils of resistance wire wound on said core and spaced longitudinally thereof, the adjacent ends of said coils being in close juxtaposition but out of electrical contact with each other, a second core mounted within said first core, a third coil of resistance wire wound on said second core, and having its opposite ends connected, respectively, to the adjacent ends of said two firstmentioned coils, and a contact member adapted to sweep said first-mentioned coils and, at times, to bridge the adjacent ends thereof, said contact member and the separated ends of said firstnamed coils being connected in an electric circuit.

3. A circuit-controlling instrument comprising a pivoted contact arm biased to move in one direction about its pivot, thermo-responsive means operable to move said arm in the opposite direction about its pivot, a pair of resistance elements arranged to be swept by the contact portion of said arm, and a third resistance element having its opposite ends connected, respectively, to one end of each of said first-mentioned elements, said third resistance element occupying a space within the space occupied by said pair of resistance elements, and the opposite ends of said first-mentioned elements being connectible 'in electric circults.

4. A device of the class described, comprising, in combination, a base, a hermetically sealed bellows having one end anchored on said base, a temperature responsive expansible fluid in said bellows whereby the free end thereof is moved conformably to changes in the temperature of the medium to which said fluid responds, a pivoted lever associated with the free end of said bellows, an electric resistance unit, a contact arm controlled by said lever and adapted to sweep said resistance unit, said resistance unit and contact arm being connected in an electric circuit, spring means biasing said lever into engagement with the free end of said bellows whereby changes in the temperature of the medium to which said expansible fluid responds results in movement of the contact arm across said resistance unit, indieating means for indicating the temperature setting of said device, and means for simultaneously adjusting said spring means and indicating means.

PAUL F. SHIVERS. 

